Burying it in Yucca Mountain

YUCCA MOUNTAIN, Nev. -- Driving northwest into the desolate vastness of the Nevada Test Site where the nation's nuclear arsenal was tested, one sees a spindly tower, outlined against a ridgeline, rising 1,527 feet out of the desert. That is the approximate height at which the atomic bomb exploded over Hiroshima. The tower was used to study radiation effects on life at different elevations.

Beyond the ridge is Frenchman Flat, where above-ground nuclear tests were a spectator sport between 1951 and 1962. Residents of Las Vegas took lawn chairs into the mountains to watch mushroom clouds rise into dawn skies. The Flat, still flecked with seared and twisted metal from vehicles and structures exposed to the blasts, is 65 miles from the Las Vegas Strip.

That is America's nuclear past. The future -- perhaps; Nevada says ``never!'' -- is beneath this mountain, 25 more miles northwest. Here a crucial component of the nation's nuclear capability, civilian and military, is being built.

So far, preparing this nuclear waste repository has cost $5 billion, most of it from fees paid by customers of utilities generating electricity by nuclear power. The rest of the money is government's payment for the military's waste.

Sculpting the mountain's interior -- carving 41 miles of storage tunnels and 16 miles of access tunnels -- and doing the science to gauge its geologic suitability is a challenge almost as daunting as the construction of the Panama Canal. It is supposed to solve this problem:

One-fifth of the nation's electricity is generated by nuclear power. Were that share substantially increased, that would reduce dependence on fuels (oil, coal, natural gas) that have large environmental and geopolitical drawbacks. Also, 40 percent of the Navy's fleet is nuclear-powered. Nuclear power plants have created almost 50,000 metric tons of spent fuel, with more produced daily. Once solidified, today's 100 million gallons of nuclear waste from prior reprocessing activities will also be placed in the repository.

Nuclear waste is stored at 125 above-ground -- inherently temporary and insecure -- sites located in 39 states, mostly near rivers, lakes and seacoasts, and within 75 miles of 161 million Americans. Most nuclear power plants are located near population centers to reduce the loss of power during transmission.

The waste might be buried in this mountain, 1,000 feet underground and on 1,000 feet of rock, for at least 10,000 years. One can only say ``might be'' because the regulatory process -- which already has taken more than twice as much time as it took to plan and accomplish the moon landing, and which is now a matter of dueling scientists -- might last 10,001 years.

The dueling is about whether safe storage of the waste can be guaranteed for 10,000 years, or perhaps a million years -- the span of projected geological stability for the mountain area. That is quite a while: 10,000 years ago, agriculture was just being born as humans, moving beyond a hunter-gatherer economy, were learning to domesticate plants.

Nevada asks: Can the safekeeping of the waste be absolute, forever? The answer, of course, is no -- nothing is that certain. The Nuclear Regulatory Commission will decide whether the repository can begin receiving waste after evaluating scientific studies conducted within the bowels of this mountain. Two federal agencies are investigating accusations that some federal scientists falsified data to make the mountain seem safe.

Storing nuclear waste, which decays very slowly and emits great heat while doing so, has been studied since 1955, when nuclear submarine propulsion technology was adapted to generate electricity. After considering storage on the seabed or a remote island or in the polar ice sheets, or rocketing the waste into orbit around the sun, deep geologic storage became the preferred solution. Some Kansas salt mines were considered, but the mines were too difficult to seal and, besides, Kansas became, as Nevada is now, obstreperous.

The crucial questions are how water permeates this mountain, and how heat from the waste might affect the mountain's hydrology. The federal government's case for this mountain's suitability is:

The volcanic and seismic risks are factored into designs. Average annual precipitation is very low, 7.5 inches, 95 percent of which runs off the mountain or into vegetation root systems. Even assuming that coming millennia will be slightly cooler, hence wetter -- the evidence of fossilized pack rats' nests at least 35,000 years old -- hydrological and chemical conditions in the mountain would cause corrosion of just 0.03 inches in 10,000 years, such is the metallurgical sophistication of the proposed waste containers.

Scientists here say their confidence in the repository's safety rests on assumptions that ``are almost absurdly conservative.'' Nevada's vehement disagreement will be examined in a subsequent column.